Today's typical processor includes special purpose memories provided to enhance ease of use and performance of the processor. Included among these memories are a boot memory--typically a read only memory (ROM)--that stores a boot program whose execution by the processor's central processing unit (CPU) upon system power-up or reset automatically initializes the CPU, and a cache memory--implemented as a random access memory (RAM)--that serves during normal processor operation as a high-speed buffer for information--illustratively either or both data and instructions--passing between the CPU and the processor's main on-line memory.
Storage devices used to implement such memories add to the cost of the processor, and also occupy valuable circuit board space. The latter is especially a serious consideration in the case of single-board processors, where a whole processor is implemented on a single circuit board. In such processors, providing of such special-purpose memories may potentially be done only at the sacrifice of some other processor capabilities, because circuit board space may not be available for circuitry needed to implement both.
Accordingly, it is a problem in the prior art to provide special-purpose memory functions in a processor with the minimum number of memory devices so as to minimize processor cost and to occupy minimum circuit board space.